1. Field of the Invention
The present invention relates to a scanning microscope.
2. Description of the Related Art
In recent years, as a microscope that enables the observation of a deep portion of a biological sample, a multi-photon excitation microscope that is represented by a two-photon excitation microscope has been attracting attention. The multi-photon excitation microscope is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2011-022299.
An extremely high photon density is required for the occurrence of a multi-photon excitation phenomenon, and therefore, in a multi-photon excitation microscope utilizing the multi-photon excitation phenomenon, fluorescence is generated from one point (an extremely narrow range) in a sample. Accordingly, unlike a confocal microscope, the multi-photon excitation microscope does not need a descanning process for returning fluorescence to the same scanning optical path as that of excitation light so as to detect the fluorescence, and can detect the fluorescence without performing the descanning process. A detector that detects observation light (fluorescence) without the need for the descanning process in a scanning microscope is referred to as a “non-descanned detector”. Detecting observation light (fluorescence) without the need for the descanning process is referred to as “non-descanned detection”.
The multi-photon excitation microscope can also obtain a bright image of a sample in which fluorescence is scattered, by guiding fluorescence from as wide a range as possible of the sample to a non-descanned detector. Therefore, in order to also guide fluorescence that is made incident on an objective from the outside of an axis to a non-descanned detector, the non-descanned detector is usually arranged such that a light receiving surface is located on a plane that is optically conjugate with a pupil of the objective.